I-Corps: Strain-Sensing Smart Skin - a New Technology for Strain Measurement

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The broader impact/commercial potential of this I-Corps project is the development of strain measurement technology that uses carbon nanotubes. Strain measurements are used in a wide variety of heavy industries, including aerospace, bridge maintenance, pipeline and chemical plant safety inspections, wind turbine monitoring, and others. Strain technologies are needed for testing critical structures and for routine maintenance inspections of infrastructure exposed to large stresses/strains. The proposed technology is a strain-sensing smart skin, a non-contact, laser-based sensor that uses carbon nanotubes. The sensor's performance may allow improved non-destructive evaluation and testing, leading to reduced failure rates and greater safety of critical infrastructure. Because many of the applications involve safety certifications, strain measurements have great societal value in helping to prevent catastrophic structural failures that may claim human life and incur significant costs.This I-Corps project is based on the development of a strain measurement technology called strain-sensing smart skin. The technology uses a sensing layer consisting of single-wall carbon nanotubes embedded in a polymeric host that is applied to the surface of metallic, plastic, composite, or cement-based substrates. After curing, subsequent strains in the substrate are transmitted through the film to the nanotubes, perturbing their electronic structures and shifting their characteristic near-infrared emission in systematic and predictable ways. Laser excitation at any points of interest induces emission the from nanotubes at those locations, and the emitted light is spectrally analyzed to reveal the local strain value. The strain values may be compiled to form two-dimensional strain maps. This method may have a significant advantage over digital image correlation (DIC), the only strain mapping method in common industrial use. DIC requires the specimen to stay under constant observation while the proposed technology does not have this requirement. This means that the proposed technology may be used to measure strains that have accumulated in service (e.g., ground maintenance inspections of aircraft).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.